1. Field of the Invention
The present invention relates generally to a resource mapping method and apparatus of an Orthogonal Frequency Division Multiplexing (OFDM) communication system and, more particularly, to a method and apparatus for allocating uplink ACK/NACK response channel resource for control channel supporting Spatial Division Multiplexing Access (SDMA).
2. Description of the Related Art
Mobile communication systems have developed to provide subscribers with voice communication services, on the move. As the technologies have advanced, mobile communications have evolved to support high-speed data communication services as well as the standard voice communication services. However, there is a need of a more sophisticated mobile communication system to mitigate resource shortage and meet the high-speed service requirements of the subscribers.
Long Term Evolution (LTE) is a next generation broadband communication technology developed by the 3rd Generation Partnership Project (3GPP). LTE is designed to provide for a downlink speed of up to 100 Mbps and is expected to be commercially launched in 2010. In order to fulfill the requirements for the LTE systems, studies have been done in various aspects including minimization of the number of involved nodes in the connections and placing the radio protocol as close as to the radio channels.
Inter-Cell-Interference-Coordination (ICIC) is a technique introduced in LTE to reduce Inter-Cell Interference (ICI) by sharing information on the currently used data channel resource among the cells, thereby keeping the inter-cell interferences under control of base station. In an LTE system, the resource is assigned to each user in unit of Resource Block (RB) for data channel but distributively across the entire system bandwidth in unit of Resource Element Group (REG) for control channel, it is impossible to apply the ICIC for control channel. In contrast, the LTE-Advanced (LTE-A) system as the evolved version of LTE system supports the extended control channel so as to configure the control channel in consideration of ICIIC. Such a control channel is assigned in a similar way to the data channel so as to make possible to use spatial multiplexing of the control channel with multi-antenna and beamforming unlike the LTE control channel. The resource extended by spatial multiplexing cannot be assigned for the uplink ACK/NACK channel which is configured by mapping to an individual Control Channel Element (CCE) one by one in the legacy LTE control channel. There is therefore a need of a method for making possible to configure channel between the control channel supporting spatial multiplexing and uplink ACK/NACK channel in the LTE-A and multiplexing the uplink ACK/NACK channels in the legacy LTE system.